The present invention generally relates to mixing fluids. More specifically, the invention relates to the continuous mixing of two fluids in a variable proportion into an exit stream.
The proportional mixing of fluids by automatic, self-powered devices is known. Such a device can be used to mix a fluid stream, such as water, with another fluid such as drugs, vaccines, nutrients, treating agents, powders, biologicals or the like. Traditional self-powered proportioners have a fluid motor and slave pump.
In a traditional self-powered proportioner, the pressure of a first fluid stream, such as water, is used to power the device. The first fluid stream cyclically moves a motor piston within a cylinder, automatically metering an amount of the first fluid with each stroke by filling the cylinder with fluid. A gating device alternates the fluid intake from one side of the motor piston to the other. Intake fluid pressure causes the motor piston to move, while fluid on the opposite side of the motor piston is simultaneously expelled. In one cycle of the proportioner, two displacements of the first fluid are expelled from the cylinder into the exit stream.
Traditional proportioners utilize a shielded grease filled bearing around the gating device in areas where the gating device enters the fluid motor. The grease and the non contacting shield are applied as a seal to prevent the first fluid from entering the bearing. Further, the grease is applied as a seal to prevent the first fluid contacting the rotating bearings not positioned within the fluid motor in an improved movement of the gating device and improved work life. Incorporating grease as a seal contains deficiencies however. The grease easily breaks down over time resulting in the first fluid escaping into the bearing. Accordingly, this grease breakdown leads to inefficient operation of the proportioner Further, the grease breakdown leads to the leaking of the bearing assembly resulting in contamination of the driving fluid. Further, in traditional proportioners, the fluid motor is not protected from impact during installation of the gating device bearings. As such, when the gating device is installed inside the fluid motor, the gating device directly impacts the bearings and distorts the internal races.
In known proportioners, the motor piston powers a slave pump. The slave pump has a slave piston and slave cylinder. The slave piston has one working side, compared to the motor piston which has two. The slave pump draws in an amount of a second fluid through an intake, then expels the second fluid through an outlet into the exit stream. The expelled second fluid mixes with the first fluid expelled from the motor piston. Proportioners commonly used in the industry use a checkball at the inlet and outlet of the slave pump. An O-ring is positioned around the inlet/outlet to seal the inlet/outlet when acted upon by the checkball. The O-ring is positioned such that the O-ring contacts the checkball in the same plane. This positioning however leads to a shorter work life of the O-ring as the checkball completely deforms the O-ring during each cycle. Because of the complete deformation, the O-ring deteriorates further resulting in a less efficient seal. Additionally, this positioning and deformation results in the checkball frequently adhering to the O-ring as the checkball contacts the O-ring head on resulting in reduced flow.
In known proportioners, the slave piston is driven by a connecting rod that is connected to the motor piston. In the proportioner disclosed in U.S. Pat. No. 4,572,229, a cavity in the housing surrounding the connecting rod acts as a fluid conduit between the motor cylinder and the back of the slave piston. Thus, the back of the slave piston is exposed to the same fluid pressure as one side of the motor piston. Thus, to achieve the desired movement, the area of the motor piston is larger than the area of the slave piston.
To achieve lower mixing ratios, traditional proportioners utilize the slave piston which has a larger area than in the proportioner described above. A larger slave piston area, though, results in a larger inefficiency, because a larger slave piston has a larger back-pressure force acting on it. If the slave piston is too large in relation to the motor piston, the power of the fluid motor cannot overcome the slave piston back-pressure and internal friction, stalling the proportioner.
Further, traditional proportioners use a motor piston which directly engages the cylinder causing increased friction resulting in lower performance and a reduction in capacity. Traditional proportioners utilize an O-ring, typically buna, as a seal on the piston. This O-ring configuration contains deficiencies, however. As the piston stops at each stroke to change direction, the O-ring adheres to the cylinder wall. Thus, force by the driving fluid must first overcome the adhesion before driving the piston in the opposite direction. Accordingly, at the end of the next stroke prior to changing direction, the O-ring again adheres to the cylinder wall. Consequently, an inefficient rocking motion develops within the piston resulting in an elliptical as opposed to circular action on the O-ring which distorts the O-ring. This rocking motion is most acute at the far end of the stroke. Because of the distortion, the O-ring wears more quickly requiring frequent replacement. A lubricant cannot be used inside the fluid motor because it would mix with the first fluid. Accordingly, the motor piston reciprocates with less efficiency.
Thus, proportioners provide constant and variable proportions of the first and second fluids mixed in each cycle. Common proportioners are described in U.S. Pat. Nos. 4,572,229, 5,433,240, issued to Thomas D. Mueller, and U.S. Pat. Nos. 3,114,379, 3,131,707, 3,213,796, 3,213,873 and 3,291,066 issued to Nat Cordis, which are incorporated herein by reference. The present invention is an improvement thereof.
A need exists for a proportioner with maximized efficiency. A need also exists for a self-powered proportioner that can mix fluids in variable ratios. A need also exists in a proportioner with an improved seal to prevent the first fluid from escaping the proportioner. Further, a need exists to protect the proportioner during installation of the gate device. Additionally, a need exists in the art for a more efficient motor piston. A need also exists for a more efficient flow of the second fluid.
The present invention provides a proportioner which overcomes the above described deficiencies of known proportioners. More specifically, the present invention relates to an improved proportioner. To this end, in an embodiment, a portable self-powered fluid proportioning device is provided. A fluid supply conduit supplies a first fluid to a body. A fluid gate is disposed within the body intermediate the fluid supply and a motor piston to cause reciprocating movement of the motor piston within a motor cylinder.
A connecting rod is secured to the motor piston for movement therewith. A slave pump has a slave piston secured to the connecting rod for providing responsive reciprocatory movement of the slave piston within slave cylinder for pumping a second fluid.
A proportioning device is provided with a body which is configured to direct a first fluid within an interior of the body wherein at least one fluid gate housing is removably fixed to the body. In the preferred embodiment, the at least one fluid gate housing comprises a first fluid gate housing and a second fluid gate housing located opposite each other on the body. Further, in the preferred embodiment, an isolated bearing is pressurably fitted within the at least one fluid gate housing. Additionally, the proportioning device includes a seal positioned between the interior of the body and the bearing. The at least one fluid gate housing has a first end and a second end, the first end is configured in a first circle shape defining a first aperture therethrough, the second end is configured in a second circle shape defining a second aperture therethrough, where the second aperture is configured smaller than the first aperture.
Further, in the preferred embodiment, the bearing fits inside the at least one fluid gate housing upon a seat. The bearing has an external race and an internal race, the external race is pressurably positioned within the first aperture while the internal race is configured to rotate with the fluid gate to reduce friction of the fluid gate.
In a preferred embodiment, the proportioning device is provided wherein the motor piston is sealably disposed within the motor cylinder in which the motor piston has a cap attached at an end. The cap has a concave annular groove with a seal surroundably disposed around the concave annular groove. The seal radially extends beyond the cap to pressurably engage against the motor cylinder in which the cap reduces friction between the motor piston and motor cylinder.
In an embodiment, a proportioning device is provided with an inlet valve. The inlet valve comprises an inlet checkball and an inlet spring within an inlet duct having at least one elongated channel, wherein the inlet checkball is normally biased by the inlet spring against an inlet seal. The inlet valve permits flow into the slave cylinder through the inlet duct, but prevents flow out of the inlet duct.
In an embodiment, a proportioning device is provided with an outlet valve. The outlet valve comprises an outlet checkball within an outlet duct having at least one elongated channel wherein the outlet checkball is normally biased by the outlet spring against an outlet seal. The outlet valve permits flow out of the slave cylinder through the outlet duct, but prevents flow into the slave cylinder through the outlet duct.
In an embodiment, a proportioning device is provided wherein the inlet valve and the outlet valve have an inlet orifice and an outlet orifice respectively. Further, in the embodiment, an inlet raised base is surroundably attached to the inlet orifice while an outlet raised base is surroundably attached to the outlet orifice.
It is, therefore, an advantage of the present invention to provide a proportioning device that is efficient.
An additional advantage of the present invention is to provide a fluid gate housing and bearing to seal the first fluid inside the body. Further, an advantage of the present invention is to provide protection of the body during installation of the fluid gate.
A further advantage of the present invention is to provide a motor piston which reduces friction between the motor cylinder.
A still further advantage of the present invention is to provide a more efficient slave pump by providing an inlet raised base and an outlet raised base within the inlet valve and the outlet valve.